Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 1014 insertions, 0 deletions

diff --git a/kernel/drivers/misc/sgi-xp/xpc_channel.c b/kernel/drivers/misc/sgi-xp/xpc_channel.c
new file mode 100644
index 000000000..128d5615c
--- /dev/null
+++ b/kernel/drivers/misc/sgi-xp/xpc_channel.c
@@ -0,0 +1,1014 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (c) 2004-2009 Silicon Graphics, Inc.  All Rights Reserved.
+ */
+
+/*
+ * Cross Partition Communication (XPC) channel support.
+ *
+ *	This is the part of XPC that manages the channels and
+ *	sends/receives messages across them to/from other partitions.
+ *
+ */
+
+#include <linux/device.h>
+#include "xpc.h"
+
+/*
+ * Process a connect message from a remote partition.
+ *
+ * Note: xpc_process_connect() is expecting to be called with the
+ * spin_lock_irqsave held and will leave it locked upon return.
+ */
+static void
+xpc_process_connect(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	enum xp_retval ret;
+
+	DBUG_ON(!spin_is_locked(&ch->lock));
+
+	if (!(ch->flags & XPC_C_OPENREQUEST) ||
+	    !(ch->flags & XPC_C_ROPENREQUEST)) {
+		/* nothing more to do for now */
+		return;
+	}
+	DBUG_ON(!(ch->flags & XPC_C_CONNECTING));
+
+	if (!(ch->flags & XPC_C_SETUP)) {
+		spin_unlock_irqrestore(&ch->lock, *irq_flags);
+		ret = xpc_arch_ops.setup_msg_structures(ch);
+		spin_lock_irqsave(&ch->lock, *irq_flags);
+
+		if (ret != xpSuccess)
+			XPC_DISCONNECT_CHANNEL(ch, ret, irq_flags);
+		else
+			ch->flags |= XPC_C_SETUP;
+
+		if (ch->flags & XPC_C_DISCONNECTING)
+			return;
+	}
+
+	if (!(ch->flags & XPC_C_OPENREPLY)) {
+		ch->flags |= XPC_C_OPENREPLY;
+		xpc_arch_ops.send_chctl_openreply(ch, irq_flags);
+	}
+
+	if (!(ch->flags & XPC_C_ROPENREPLY))
+		return;
+
+	if (!(ch->flags & XPC_C_OPENCOMPLETE)) {
+		ch->flags |= (XPC_C_OPENCOMPLETE | XPC_C_CONNECTED);
+		xpc_arch_ops.send_chctl_opencomplete(ch, irq_flags);
+	}
+
+	if (!(ch->flags & XPC_C_ROPENCOMPLETE))
+		return;
+
+	dev_info(xpc_chan, "channel %d to partition %d connected\n",
+		 ch->number, ch->partid);
+
+	ch->flags = (XPC_C_CONNECTED | XPC_C_SETUP);	/* clear all else */
+}
+
+/*
+ * spin_lock_irqsave() is expected to be held on entry.
+ */
+static void
+xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	struct xpc_partition *part = &xpc_partitions[ch->partid];
+	u32 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);
+
+	DBUG_ON(!spin_is_locked(&ch->lock));
+
+	if (!(ch->flags & XPC_C_DISCONNECTING))
+		return;
+
+	DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
+
+	/* make sure all activity has settled down first */
+
+	if (atomic_read(&ch->kthreads_assigned) > 0 ||
+	    atomic_read(&ch->references) > 0) {
+		return;
+	}
+	DBUG_ON((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
+		!(ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE));
+
+	if (part->act_state == XPC_P_AS_DEACTIVATING) {
+		/* can't proceed until the other side disengages from us */
+		if (xpc_arch_ops.partition_engaged(ch->partid))
+			return;
+
+	} else {
+
+		/* as long as the other side is up do the full protocol */
+
+		if (!(ch->flags & XPC_C_RCLOSEREQUEST))
+			return;
+
+		if (!(ch->flags & XPC_C_CLOSEREPLY)) {
+			ch->flags |= XPC_C_CLOSEREPLY;
+			xpc_arch_ops.send_chctl_closereply(ch, irq_flags);
+		}
+
+		if (!(ch->flags & XPC_C_RCLOSEREPLY))
+			return;
+	}
+
+	/* wake those waiting for notify completion */
+	if (atomic_read(&ch->n_to_notify) > 0) {
+		/* we do callout while holding ch->lock, callout can't block */
+		xpc_arch_ops.notify_senders_of_disconnect(ch);
+	}
+
+	/* both sides are disconnected now */
+
+	if (ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE) {
+		spin_unlock_irqrestore(&ch->lock, *irq_flags);
+		xpc_disconnect_callout(ch, xpDisconnected);
+		spin_lock_irqsave(&ch->lock, *irq_flags);
+	}
+
+	DBUG_ON(atomic_read(&ch->n_to_notify) != 0);
+
+	/* it's now safe to free the channel's message queues */
+	xpc_arch_ops.teardown_msg_structures(ch);
+
+	ch->func = NULL;
+	ch->key = NULL;
+	ch->entry_size = 0;
+	ch->local_nentries = 0;
+	ch->remote_nentries = 0;
+	ch->kthreads_assigned_limit = 0;
+	ch->kthreads_idle_limit = 0;
+
+	/*
+	 * Mark the channel disconnected and clear all other flags, including
+	 * XPC_C_SETUP (because of call to
+	 * xpc_arch_ops.teardown_msg_structures()) but not including
+	 * XPC_C_WDISCONNECT (if it was set).
+	 */
+	ch->flags = (XPC_C_DISCONNECTED | (ch->flags & XPC_C_WDISCONNECT));
+
+	atomic_dec(&part->nchannels_active);
+
+	if (channel_was_connected) {
+		dev_info(xpc_chan, "channel %d to partition %d disconnected, "
+			 "reason=%d\n", ch->number, ch->partid, ch->reason);
+	}
+
+	if (ch->flags & XPC_C_WDISCONNECT) {
+		/* we won't lose the CPU since we're holding ch->lock */
+		complete(&ch->wdisconnect_wait);
+	} else if (ch->delayed_chctl_flags) {
+		if (part->act_state != XPC_P_AS_DEACTIVATING) {
+			/* time to take action on any delayed chctl flags */
+			spin_lock(&part->chctl_lock);
+			part->chctl.flags[ch->number] |=
+			    ch->delayed_chctl_flags;
+			spin_unlock(&part->chctl_lock);
+		}
+		ch->delayed_chctl_flags = 0;
+	}
+}
+
+/*
+ * Process a change in the channel's remote connection state.
+ */
+static void
+xpc_process_openclose_chctl_flags(struct xpc_partition *part, int ch_number,
+				  u8 chctl_flags)
+{
+	unsigned long irq_flags;
+	struct xpc_openclose_args *args =
+	    &part->remote_openclose_args[ch_number];
+	struct xpc_channel *ch = &part->channels[ch_number];
+	enum xp_retval reason;
+	enum xp_retval ret;
+	int create_kthread = 0;
+
+	spin_lock_irqsave(&ch->lock, irq_flags);
+
+again:
+
+	if ((ch->flags & XPC_C_DISCONNECTED) &&
+	    (ch->flags & XPC_C_WDISCONNECT)) {
+		/*
+		 * Delay processing chctl flags until thread waiting disconnect
+		 * has had a chance to see that the channel is disconnected.
+		 */
+		ch->delayed_chctl_flags |= chctl_flags;
+		goto out;
+	}
+
+	if (chctl_flags & XPC_CHCTL_CLOSEREQUEST) {
+
+		dev_dbg(xpc_chan, "XPC_CHCTL_CLOSEREQUEST (reason=%d) received "
+			"from partid=%d, channel=%d\n", args->reason,
+			ch->partid, ch->number);
+
+		/*
+		 * If RCLOSEREQUEST is set, we're probably waiting for
+		 * RCLOSEREPLY. We should find it and a ROPENREQUEST packed
+		 * with this RCLOSEREQUEST in the chctl_flags.
+		 */
+
+		if (ch->flags & XPC_C_RCLOSEREQUEST) {
+			DBUG_ON(!(ch->flags & XPC_C_DISCONNECTING));
+			DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
+			DBUG_ON(!(ch->flags & XPC_C_CLOSEREPLY));
+			DBUG_ON(ch->flags & XPC_C_RCLOSEREPLY);
+
+			DBUG_ON(!(chctl_flags & XPC_CHCTL_CLOSEREPLY));
+			chctl_flags &= ~XPC_CHCTL_CLOSEREPLY;
+			ch->flags |= XPC_C_RCLOSEREPLY;
+
+			/* both sides have finished disconnecting */
+			xpc_process_disconnect(ch, &irq_flags);
+			DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
+			goto again;
+		}
+
+		if (ch->flags & XPC_C_DISCONNECTED) {
+			if (!(chctl_flags & XPC_CHCTL_OPENREQUEST)) {
+				if (part->chctl.flags[ch_number] &
+				    XPC_CHCTL_OPENREQUEST) {
+
+					DBUG_ON(ch->delayed_chctl_flags != 0);
+					spin_lock(&part->chctl_lock);
+					part->chctl.flags[ch_number] |=
+					    XPC_CHCTL_CLOSEREQUEST;
+					spin_unlock(&part->chctl_lock);
+				}
+				goto out;
+			}
+
+			XPC_SET_REASON(ch, 0, 0);
+			ch->flags &= ~XPC_C_DISCONNECTED;
+
+			atomic_inc(&part->nchannels_active);
+			ch->flags |= (XPC_C_CONNECTING | XPC_C_ROPENREQUEST);
+		}
+
+		chctl_flags &= ~(XPC_CHCTL_OPENREQUEST | XPC_CHCTL_OPENREPLY |
+		    XPC_CHCTL_OPENCOMPLETE);
+
+		/*
+		 * The meaningful CLOSEREQUEST connection state fields are:
+		 *      reason = reason connection is to be closed
+		 */
+
+		ch->flags |= XPC_C_RCLOSEREQUEST;
+
+		if (!(ch->flags & XPC_C_DISCONNECTING)) {
+			reason = args->reason;
+			if (reason <= xpSuccess || reason > xpUnknownReason)
+				reason = xpUnknownReason;
+			else if (reason == xpUnregistering)
+				reason = xpOtherUnregistering;
+
+			XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
+
+			DBUG_ON(chctl_flags & XPC_CHCTL_CLOSEREPLY);
+			goto out;
+		}
+
+		xpc_process_disconnect(ch, &irq_flags);
+	}
+
+	if (chctl_flags & XPC_CHCTL_CLOSEREPLY) {
+
+		dev_dbg(xpc_chan, "XPC_CHCTL_CLOSEREPLY received from partid="
+			"%d, channel=%d\n", ch->partid, ch->number);
+
+		if (ch->flags & XPC_C_DISCONNECTED) {
+			DBUG_ON(part->act_state != XPC_P_AS_DEACTIVATING);
+			goto out;
+		}
+
+		DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
+
+		if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
+			if (part->chctl.flags[ch_number] &
+			    XPC_CHCTL_CLOSEREQUEST) {
+
+				DBUG_ON(ch->delayed_chctl_flags != 0);
+				spin_lock(&part->chctl_lock);
+				part->chctl.flags[ch_number] |=
+				    XPC_CHCTL_CLOSEREPLY;
+				spin_unlock(&part->chctl_lock);
+			}
+			goto out;
+		}
+
+		ch->flags |= XPC_C_RCLOSEREPLY;
+
+		if (ch->flags & XPC_C_CLOSEREPLY) {
+			/* both sides have finished disconnecting */
+			xpc_process_disconnect(ch, &irq_flags);
+		}
+	}
+
+	if (chctl_flags & XPC_CHCTL_OPENREQUEST) {
+
+		dev_dbg(xpc_chan, "XPC_CHCTL_OPENREQUEST (entry_size=%d, "
+			"local_nentries=%d) received from partid=%d, "
+			"channel=%d\n", args->entry_size, args->local_nentries,
+			ch->partid, ch->number);
+
+		if (part->act_state == XPC_P_AS_DEACTIVATING ||
+		    (ch->flags & XPC_C_ROPENREQUEST)) {
+			goto out;
+		}
+
+		if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_WDISCONNECT)) {
+			ch->delayed_chctl_flags |= XPC_CHCTL_OPENREQUEST;
+			goto out;
+		}
+		DBUG_ON(!(ch->flags & (XPC_C_DISCONNECTED |
+				       XPC_C_OPENREQUEST)));
+		DBUG_ON(ch->flags & (XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
+				     XPC_C_OPENREPLY | XPC_C_CONNECTED));
+
+		/*
+		 * The meaningful OPENREQUEST connection state fields are:
+		 *      entry_size = size of channel's messages in bytes
+		 *      local_nentries = remote partition's local_nentries
+		 */
+		if (args->entry_size == 0 || args->local_nentries == 0) {
+			/* assume OPENREQUEST was delayed by mistake */
+			goto out;
+		}
+
+		ch->flags |= (XPC_C_ROPENREQUEST | XPC_C_CONNECTING);
+		ch->remote_nentries = args->local_nentries;
+
+		if (ch->flags & XPC_C_OPENREQUEST) {
+			if (args->entry_size != ch->entry_size) {
+				XPC_DISCONNECT_CHANNEL(ch, xpUnequalMsgSizes,
+						       &irq_flags);
+				goto out;
+			}
+		} else {
+			ch->entry_size = args->entry_size;
+
+			XPC_SET_REASON(ch, 0, 0);
+			ch->flags &= ~XPC_C_DISCONNECTED;
+
+			atomic_inc(&part->nchannels_active);
+		}
+
+		xpc_process_connect(ch, &irq_flags);
+	}
+
+	if (chctl_flags & XPC_CHCTL_OPENREPLY) {
+
+		dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY (local_msgqueue_pa="
+			"0x%lx, local_nentries=%d, remote_nentries=%d) "
+			"received from partid=%d, channel=%d\n",
+			args->local_msgqueue_pa, args->local_nentries,
+			args->remote_nentries, ch->partid, ch->number);
+
+		if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED))
+			goto out;
+
+		if (!(ch->flags & XPC_C_OPENREQUEST)) {
+			XPC_DISCONNECT_CHANNEL(ch, xpOpenCloseError,
+					       &irq_flags);
+			goto out;
+		}
+
+		DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
+		DBUG_ON(ch->flags & XPC_C_CONNECTED);
+
+		/*
+		 * The meaningful OPENREPLY connection state fields are:
+		 *      local_msgqueue_pa = physical address of remote
+		 *                          partition's local_msgqueue
+		 *      local_nentries = remote partition's local_nentries
+		 *      remote_nentries = remote partition's remote_nentries
+		 */
+		DBUG_ON(args->local_msgqueue_pa == 0);
+		DBUG_ON(args->local_nentries == 0);
+		DBUG_ON(args->remote_nentries == 0);
+
+		ret = xpc_arch_ops.save_remote_msgqueue_pa(ch,
+						      args->local_msgqueue_pa);
+		if (ret != xpSuccess) {
+			XPC_DISCONNECT_CHANNEL(ch, ret, &irq_flags);
+			goto out;
+		}
+		ch->flags |= XPC_C_ROPENREPLY;
+
+		if (args->local_nentries < ch->remote_nentries) {
+			dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY: new "
+				"remote_nentries=%d, old remote_nentries=%d, "
+				"partid=%d, channel=%d\n",
+				args->local_nentries, ch->remote_nentries,
+				ch->partid, ch->number);
+
+			ch->remote_nentries = args->local_nentries;
+		}
+		if (args->remote_nentries < ch->local_nentries) {
+			dev_dbg(xpc_chan, "XPC_CHCTL_OPENREPLY: new "
+				"local_nentries=%d, old local_nentries=%d, "
+				"partid=%d, channel=%d\n",
+				args->remote_nentries, ch->local_nentries,
+				ch->partid, ch->number);
+
+			ch->local_nentries = args->remote_nentries;
+		}
+
+		xpc_process_connect(ch, &irq_flags);
+	}
+
+	if (chctl_flags & XPC_CHCTL_OPENCOMPLETE) {
+
+		dev_dbg(xpc_chan, "XPC_CHCTL_OPENCOMPLETE received from "
+			"partid=%d, channel=%d\n", ch->partid, ch->number);
+
+		if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED))
+			goto out;
+
+		if (!(ch->flags & XPC_C_OPENREQUEST) ||
+		    !(ch->flags & XPC_C_OPENREPLY)) {
+			XPC_DISCONNECT_CHANNEL(ch, xpOpenCloseError,
+					       &irq_flags);
+			goto out;
+		}
+
+		DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
+		DBUG_ON(!(ch->flags & XPC_C_ROPENREPLY));
+		DBUG_ON(!(ch->flags & XPC_C_CONNECTED));
+
+		ch->flags |= XPC_C_ROPENCOMPLETE;
+
+		xpc_process_connect(ch, &irq_flags);
+		create_kthread = 1;
+	}
+
+out:
+	spin_unlock_irqrestore(&ch->lock, irq_flags);
+
+	if (create_kthread)
+		xpc_create_kthreads(ch, 1, 0);
+}
+
+/*
+ * Attempt to establish a channel connection to a remote partition.
+ */
+static enum xp_retval
+xpc_connect_channel(struct xpc_channel *ch)
+{
+	unsigned long irq_flags;
+	struct xpc_registration *registration = &xpc_registrations[ch->number];
+
+	if (mutex_trylock(&registration->mutex) == 0)
+		return xpRetry;
+
+	if (!XPC_CHANNEL_REGISTERED(ch->number)) {
+		mutex_unlock(&registration->mutex);
+		return xpUnregistered;
+	}
+
+	spin_lock_irqsave(&ch->lock, irq_flags);
+
+	DBUG_ON(ch->flags & XPC_C_CONNECTED);
+	DBUG_ON(ch->flags & XPC_C_OPENREQUEST);
+
+	if (ch->flags & XPC_C_DISCONNECTING) {
+		spin_unlock_irqrestore(&ch->lock, irq_flags);
+		mutex_unlock(&registration->mutex);
+		return ch->reason;
+	}
+
+	/* add info from the channel connect registration to the channel */
+
+	ch->kthreads_assigned_limit = registration->assigned_limit;
+	ch->kthreads_idle_limit = registration->idle_limit;
+	DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
+	DBUG_ON(atomic_read(&ch->kthreads_idle) != 0);
+	DBUG_ON(atomic_read(&ch->kthreads_active) != 0);
+
+	ch->func = registration->func;
+	DBUG_ON(registration->func == NULL);
+	ch->key = registration->key;
+
+	ch->local_nentries = registration->nentries;
+
+	if (ch->flags & XPC_C_ROPENREQUEST) {
+		if (registration->entry_size != ch->entry_size) {
+			/* the local and remote sides aren't the same */
+
+			/*
+			 * Because XPC_DISCONNECT_CHANNEL() can block we're
+			 * forced to up the registration sema before we unlock
+			 * the channel lock. But that's okay here because we're
+			 * done with the part that required the registration
+			 * sema. XPC_DISCONNECT_CHANNEL() requires that the
+			 * channel lock be locked and will unlock and relock
+			 * the channel lock as needed.
+			 */
+			mutex_unlock(&registration->mutex);
+			XPC_DISCONNECT_CHANNEL(ch, xpUnequalMsgSizes,
+					       &irq_flags);
+			spin_unlock_irqrestore(&ch->lock, irq_flags);
+			return xpUnequalMsgSizes;
+		}
+	} else {
+		ch->entry_size = registration->entry_size;
+
+		XPC_SET_REASON(ch, 0, 0);
+		ch->flags &= ~XPC_C_DISCONNECTED;
+
+		atomic_inc(&xpc_partitions[ch->partid].nchannels_active);
+	}
+
+	mutex_unlock(&registration->mutex);
+
+	/* initiate the connection */
+
+	ch->flags |= (XPC_C_OPENREQUEST | XPC_C_CONNECTING);
+	xpc_arch_ops.send_chctl_openrequest(ch, &irq_flags);
+
+	xpc_process_connect(ch, &irq_flags);
+
+	spin_unlock_irqrestore(&ch->lock, irq_flags);
+
+	return xpSuccess;
+}
+
+void
+xpc_process_sent_chctl_flags(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	union xpc_channel_ctl_flags chctl;
+	struct xpc_channel *ch;
+	int ch_number;
+	u32 ch_flags;
+
+	chctl.all_flags = xpc_arch_ops.get_chctl_all_flags(part);
+
+	/*
+	 * Initiate channel connections for registered channels.
+	 *
+	 * For each connected channel that has pending messages activate idle
+	 * kthreads and/or create new kthreads as needed.
+	 */
+
+	for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
+		ch = &part->channels[ch_number];
+
+		/*
+		 * Process any open or close related chctl flags, and then deal
+		 * with connecting or disconnecting the channel as required.
+		 */
+
+		if (chctl.flags[ch_number] & XPC_OPENCLOSE_CHCTL_FLAGS) {
+			xpc_process_openclose_chctl_flags(part, ch_number,
+							chctl.flags[ch_number]);
+		}
+
+		ch_flags = ch->flags;	/* need an atomic snapshot of flags */
+
+		if (ch_flags & XPC_C_DISCONNECTING) {
+			spin_lock_irqsave(&ch->lock, irq_flags);
+			xpc_process_disconnect(ch, &irq_flags);
+			spin_unlock_irqrestore(&ch->lock, irq_flags);
+			continue;
+		}
+
+		if (part->act_state == XPC_P_AS_DEACTIVATING)
+			continue;
+
+		if (!(ch_flags & XPC_C_CONNECTED)) {
+			if (!(ch_flags & XPC_C_OPENREQUEST)) {
+				DBUG_ON(ch_flags & XPC_C_SETUP);
+				(void)xpc_connect_channel(ch);
+			}
+			continue;
+		}
+
+		/*
+		 * Process any message related chctl flags, this may involve
+		 * the activation of kthreads to deliver any pending messages
+		 * sent from the other partition.
+		 */
+
+		if (chctl.flags[ch_number] & XPC_MSG_CHCTL_FLAGS)
+			xpc_arch_ops.process_msg_chctl_flags(part, ch_number);
+	}
+}
+
+/*
+ * XPC's heartbeat code calls this function to inform XPC that a partition is
+ * going down.  XPC responds by tearing down the XPartition Communication
+ * infrastructure used for the just downed partition.
+ *
+ * XPC's heartbeat code will never call this function and xpc_partition_up()
+ * at the same time. Nor will it ever make multiple calls to either function
+ * at the same time.
+ */
+void
+xpc_partition_going_down(struct xpc_partition *part, enum xp_retval reason)
+{
+	unsigned long irq_flags;
+	int ch_number;
+	struct xpc_channel *ch;
+
+	dev_dbg(xpc_chan, "deactivating partition %d, reason=%d\n",
+		XPC_PARTID(part), reason);
+
+	if (!xpc_part_ref(part)) {
+		/* infrastructure for this partition isn't currently set up */
+		return;
+	}
+
+	/* disconnect channels associated with the partition going down */
+
+	for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
+		ch = &part->channels[ch_number];
+
+		xpc_msgqueue_ref(ch);
+		spin_lock_irqsave(&ch->lock, irq_flags);
+
+		XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
+
+		spin_unlock_irqrestore(&ch->lock, irq_flags);
+		xpc_msgqueue_deref(ch);
+	}
+
+	xpc_wakeup_channel_mgr(part);
+
+	xpc_part_deref(part);
+}
+
+/*
+ * Called by XP at the time of channel connection registration to cause
+ * XPC to establish connections to all currently active partitions.
+ */
+void
+xpc_initiate_connect(int ch_number)
+{
+	short partid;
+	struct xpc_partition *part;
+	struct xpc_channel *ch;
+
+	DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);
+
+	for (partid = 0; partid < xp_max_npartitions; partid++) {
+		part = &xpc_partitions[partid];
+
+		if (xpc_part_ref(part)) {
+			ch = &part->channels[ch_number];
+
+			/*
+			 * Initiate the establishment of a connection on the
+			 * newly registered channel to the remote partition.
+			 */
+			xpc_wakeup_channel_mgr(part);
+			xpc_part_deref(part);
+		}
+	}
+}
+
+void
+xpc_connected_callout(struct xpc_channel *ch)
+{
+	/* let the registerer know that a connection has been established */
+
+	if (ch->func != NULL) {
+		dev_dbg(xpc_chan, "ch->func() called, reason=xpConnected, "
+			"partid=%d, channel=%d\n", ch->partid, ch->number);
+
+		ch->func(xpConnected, ch->partid, ch->number,
+			 (void *)(u64)ch->local_nentries, ch->key);
+
+		dev_dbg(xpc_chan, "ch->func() returned, reason=xpConnected, "
+			"partid=%d, channel=%d\n", ch->partid, ch->number);
+	}
+}
+
+/*
+ * Called by XP at the time of channel connection unregistration to cause
+ * XPC to teardown all current connections for the specified channel.
+ *
+ * Before returning xpc_initiate_disconnect() will wait until all connections
+ * on the specified channel have been closed/torndown. So the caller can be
+ * assured that they will not be receiving any more callouts from XPC to the
+ * function they registered via xpc_connect().
+ *
+ * Arguments:
+ *
+ *	ch_number - channel # to unregister.
+ */
+void
+xpc_initiate_disconnect(int ch_number)
+{
+	unsigned long irq_flags;
+	short partid;
+	struct xpc_partition *part;
+	struct xpc_channel *ch;
+
+	DBUG_ON(ch_number < 0 || ch_number >= XPC_MAX_NCHANNELS);
+
+	/* initiate the channel disconnect for every active partition */
+	for (partid = 0; partid < xp_max_npartitions; partid++) {
+		part = &xpc_partitions[partid];
+
+		if (xpc_part_ref(part)) {
+			ch = &part->channels[ch_number];
+			xpc_msgqueue_ref(ch);
+
+			spin_lock_irqsave(&ch->lock, irq_flags);
+
+			if (!(ch->flags & XPC_C_DISCONNECTED)) {
+				ch->flags |= XPC_C_WDISCONNECT;
+
+				XPC_DISCONNECT_CHANNEL(ch, xpUnregistering,
+						       &irq_flags);
+			}
+
+			spin_unlock_irqrestore(&ch->lock, irq_flags);
+
+			xpc_msgqueue_deref(ch);
+			xpc_part_deref(part);
+		}
+	}
+
+	xpc_disconnect_wait(ch_number);
+}
+
+/*
+ * To disconnect a channel, and reflect it back to all who may be waiting.
+ *
+ * An OPEN is not allowed until XPC_C_DISCONNECTING is cleared by
+ * xpc_process_disconnect(), and if set, XPC_C_WDISCONNECT is cleared by
+ * xpc_disconnect_wait().
+ *
+ * THE CHANNEL IS TO BE LOCKED BY THE CALLER AND WILL REMAIN LOCKED UPON RETURN.
+ */
+void
+xpc_disconnect_channel(const int line, struct xpc_channel *ch,
+		       enum xp_retval reason, unsigned long *irq_flags)
+{
+	u32 channel_was_connected = (ch->flags & XPC_C_CONNECTED);
+
+	DBUG_ON(!spin_is_locked(&ch->lock));
+
+	if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED))
+		return;
+
+	DBUG_ON(!(ch->flags & (XPC_C_CONNECTING | XPC_C_CONNECTED)));
+
+	dev_dbg(xpc_chan, "reason=%d, line=%d, partid=%d, channel=%d\n",
+		reason, line, ch->partid, ch->number);
+
+	XPC_SET_REASON(ch, reason, line);
+
+	ch->flags |= (XPC_C_CLOSEREQUEST | XPC_C_DISCONNECTING);
+	/* some of these may not have been set */
+	ch->flags &= ~(XPC_C_OPENREQUEST | XPC_C_OPENREPLY |
+		       XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
+		       XPC_C_CONNECTING | XPC_C_CONNECTED);
+
+	xpc_arch_ops.send_chctl_closerequest(ch, irq_flags);
+
+	if (channel_was_connected)
+		ch->flags |= XPC_C_WASCONNECTED;
+
+	spin_unlock_irqrestore(&ch->lock, *irq_flags);
+
+	/* wake all idle kthreads so they can exit */
+	if (atomic_read(&ch->kthreads_idle) > 0) {
+		wake_up_all(&ch->idle_wq);
+
+	} else if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
+		   !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
+		/* start a kthread that will do the xpDisconnecting callout */
+		xpc_create_kthreads(ch, 1, 1);
+	}
+
+	/* wake those waiting to allocate an entry from the local msg queue */
+	if (atomic_read(&ch->n_on_msg_allocate_wq) > 0)
+		wake_up(&ch->msg_allocate_wq);
+
+	spin_lock_irqsave(&ch->lock, *irq_flags);
+}
+
+void
+xpc_disconnect_callout(struct xpc_channel *ch, enum xp_retval reason)
+{
+	/*
+	 * Let the channel's registerer know that the channel is being
+	 * disconnected. We don't want to do this if the registerer was never
+	 * informed of a connection being made.
+	 */
+
+	if (ch->func != NULL) {
+		dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
+			"channel=%d\n", reason, ch->partid, ch->number);
+
+		ch->func(reason, ch->partid, ch->number, NULL, ch->key);
+
+		dev_dbg(xpc_chan, "ch->func() returned, reason=%d, partid=%d, "
+			"channel=%d\n", reason, ch->partid, ch->number);
+	}
+}
+
+/*
+ * Wait for a message entry to become available for the specified channel,
+ * but don't wait any longer than 1 jiffy.
+ */
+enum xp_retval
+xpc_allocate_msg_wait(struct xpc_channel *ch)
+{
+	enum xp_retval ret;
+	DEFINE_WAIT(wait);
+
+	if (ch->flags & XPC_C_DISCONNECTING) {
+		DBUG_ON(ch->reason == xpInterrupted);
+		return ch->reason;
+	}
+
+	atomic_inc(&ch->n_on_msg_allocate_wq);
+	prepare_to_wait(&ch->msg_allocate_wq, &wait, TASK_INTERRUPTIBLE);
+	ret = schedule_timeout(1);
+	finish_wait(&ch->msg_allocate_wq, &wait);
+	atomic_dec(&ch->n_on_msg_allocate_wq);
+
+	if (ch->flags & XPC_C_DISCONNECTING) {
+		ret = ch->reason;
+		DBUG_ON(ch->reason == xpInterrupted);
+	} else if (ret == 0) {
+		ret = xpTimeout;
+	} else {
+		ret = xpInterrupted;
+	}
+
+	return ret;
+}
+
+/*
+ * Send a message that contains the user's payload on the specified channel
+ * connected to the specified partition.
+ *
+ * NOTE that this routine can sleep waiting for a message entry to become
+ * available. To not sleep, pass in the XPC_NOWAIT flag.
+ *
+ * Once sent, this routine will not wait for the message to be received, nor
+ * will notification be given when it does happen.
+ *
+ * Arguments:
+ *
+ *	partid - ID of partition to which the channel is connected.
+ *	ch_number - channel # to send message on.
+ *	flags - see xp.h for valid flags.
+ *	payload - pointer to the payload which is to be sent.
+ *	payload_size - size of the payload in bytes.
+ */
+enum xp_retval
+xpc_initiate_send(short partid, int ch_number, u32 flags, void *payload,
+		  u16 payload_size)
+{
+	struct xpc_partition *part = &xpc_partitions[partid];
+	enum xp_retval ret = xpUnknownReason;
+
+	dev_dbg(xpc_chan, "payload=0x%p, partid=%d, channel=%d\n", payload,
+		partid, ch_number);
+
+	DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
+	DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
+	DBUG_ON(payload == NULL);
+
+	if (xpc_part_ref(part)) {
+		ret = xpc_arch_ops.send_payload(&part->channels[ch_number],
+				  flags, payload, payload_size, 0, NULL, NULL);
+		xpc_part_deref(part);
+	}
+
+	return ret;
+}
+
+/*
+ * Send a message that contains the user's payload on the specified channel
+ * connected to the specified partition.
+ *
+ * NOTE that this routine can sleep waiting for a message entry to become
+ * available. To not sleep, pass in the XPC_NOWAIT flag.
+ *
+ * This routine will not wait for the message to be sent or received.
+ *
+ * Once the remote end of the channel has received the message, the function
+ * passed as an argument to xpc_initiate_send_notify() will be called. This
+ * allows the sender to free up or re-use any buffers referenced by the
+ * message, but does NOT mean the message has been processed at the remote
+ * end by a receiver.
+ *
+ * If this routine returns an error, the caller's function will NOT be called.
+ *
+ * Arguments:
+ *
+ *	partid - ID of partition to which the channel is connected.
+ *	ch_number - channel # to send message on.
+ *	flags - see xp.h for valid flags.
+ *	payload - pointer to the payload which is to be sent.
+ *	payload_size - size of the payload in bytes.
+ *	func - function to call with asynchronous notification of message
+ *		  receipt. THIS FUNCTION MUST BE NON-BLOCKING.
+ *	key - user-defined key to be passed to the function when it's called.
+ */
+enum xp_retval
+xpc_initiate_send_notify(short partid, int ch_number, u32 flags, void *payload,
+			 u16 payload_size, xpc_notify_func func, void *key)
+{
+	struct xpc_partition *part = &xpc_partitions[partid];
+	enum xp_retval ret = xpUnknownReason;
+
+	dev_dbg(xpc_chan, "payload=0x%p, partid=%d, channel=%d\n", payload,
+		partid, ch_number);
+
+	DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
+	DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
+	DBUG_ON(payload == NULL);
+	DBUG_ON(func == NULL);
+
+	if (xpc_part_ref(part)) {
+		ret = xpc_arch_ops.send_payload(&part->channels[ch_number],
+			  flags, payload, payload_size, XPC_N_CALL, func, key);
+		xpc_part_deref(part);
+	}
+	return ret;
+}
+
+/*
+ * Deliver a message's payload to its intended recipient.
+ */
+void
+xpc_deliver_payload(struct xpc_channel *ch)
+{
+	void *payload;
+
+	payload = xpc_arch_ops.get_deliverable_payload(ch);
+	if (payload != NULL) {
+
+		/*
+		 * This ref is taken to protect the payload itself from being
+		 * freed before the user is finished with it, which the user
+		 * indicates by calling xpc_initiate_received().
+		 */
+		xpc_msgqueue_ref(ch);
+
+		atomic_inc(&ch->kthreads_active);
+
+		if (ch->func != NULL) {
+			dev_dbg(xpc_chan, "ch->func() called, payload=0x%p "
+				"partid=%d channel=%d\n", payload, ch->partid,
+				ch->number);
+
+			/* deliver the message to its intended recipient */
+			ch->func(xpMsgReceived, ch->partid, ch->number, payload,
+				 ch->key);
+
+			dev_dbg(xpc_chan, "ch->func() returned, payload=0x%p "
+				"partid=%d channel=%d\n", payload, ch->partid,
+				ch->number);
+		}
+
+		atomic_dec(&ch->kthreads_active);
+	}
+}
+
+/*
+ * Acknowledge receipt of a delivered message's payload.
+ *
+ * This function, although called by users, does not call xpc_part_ref() to
+ * ensure that the partition infrastructure is in place. It relies on the
+ * fact that we called xpc_msgqueue_ref() in xpc_deliver_payload().
+ *
+ * Arguments:
+ *
+ *	partid - ID of partition to which the channel is connected.
+ *	ch_number - channel # message received on.
+ *	payload - pointer to the payload area allocated via
+ *			xpc_initiate_send() or xpc_initiate_send_notify().
+ */
+void
+xpc_initiate_received(short partid, int ch_number, void *payload)
+{
+	struct xpc_partition *part = &xpc_partitions[partid];
+	struct xpc_channel *ch;
+
+	DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
+	DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
+
+	ch = &part->channels[ch_number];
+	xpc_arch_ops.received_payload(ch, payload);
+
+	/* the call to xpc_msgqueue_ref() was done by xpc_deliver_payload()  */
+	xpc_msgqueue_deref(ch);
+}